1. Field of the Invention
This invention relates to photoconductive materials for electrophotography, and more particularly, to photoconductive materials of high humidity resistance and having desirable electric charge transfer characteristics.
2. Description of the Prior Art
Electrophotographic photosensitive members may assume a variety of constructions depending upon the types of electophotographic processes. As a representative electrophotographic photosensitive member, there may be mentioned a photosensitive member composed of a substrate and a photoconductive layer and a photosensitive member having an insulating layer on the surface. These are widely used.
The photosensitive member composed of a substrate and a photoconductive layer is used for the most common electrophotographic process, that is, a process comprising charging, imagewise exposure, development and if desired, transfer of developed images.
An insulating layer of a photosensitive member having an insulating layer serves to protect the photoconductive layer, improve mechanical strength and dark decay characteristics, and make the photosensitive member suitable for a particular electrophotographic process or further produce a photosensitive member free from pollution.
Representative examples of such photosensitive member having an insulating layer or an electrophotographic process employing such photosensitive member are disclosed in U.S. Pat. No. 2,860,048, Japanese Patent Publication No. 16429/1966, U.S. Pat. Nos. 3,146,145, 3,607,258, 3,666,363, 3,734,609, 3,457,070 and 3,124,456 and the like.
Electrophotographic photoconductive materials are naturally required to have a particular sensitivity and optical characteristics suitable for the electrophotographic process and an improved humidity resistance. Further, in case of an electrophotographic process which comprises a step of injecting electric charges from the substrate side into between the photoconductive layer and the insulating layer upon charging, characteristics affecting lasiness of electric charge transfer in the photoconductive layer should be adjusted.